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Volume 141, 1998
53
A CONTRIBUTION TO THE ANOMALIES OF HETEROCHTONIC BACK MUSCLES
Alžběta Holibková*, Libor Machálek
Department of Anatomy, Medical Faculty, Palacký University, 775 00 Olomouc, Czech Republic
Received January 20, 1998
Key words: Back muscles / Muscles anomalies / Trapezius anomalies
Some authors described a muscular adult man with a quite large bilateral muscle originating from the front margin of the
transverse process of the C1 – C2 vertebrae and inserting to the back margin of the clavicle next to the conoid tubercle.
They named it levator claviculae.
INTRODUCTION
The anomalies of the heterochtonic back muscles are
commonly described in medical literature. We have already seen some varieties of the back muscles in our dissection material – for instance the superficial rhomboatlantic
muscle (Holibková, Machálek1) and others.
Here we would like to present an extra bilateral muscle
at the front margin of the trapezius (fig. 1, 2), which we
named levator claviculae.
Fig. 2. 1 – levator claviculae, 2 – trapezius, 3 – sternocleidomastoid,
4 – levator scapulae, 5 – omohyoid, 6 – scalenus medius,
7 – scalenus anterior, 8 – neurovascular cervical bundle
Fig. 1. 1 – levator claviculae, 2 – trapezius, 3 – sternocleidomastoid,
4 – levator scapulae, 5 – scalenus medius, 6 – omohyoid,
7 – clavicle, 8 – neurovascular cervical bundle
Dedicated to the 65th anniversary of Doc. MUDr. et RNDr. Milan Černý, CSc.
54
Acta Univ. Palacki. Olomuc., Fac. Med.
OBSERVATION AND DISCUSSION
The frequent occurence of anomalies in this area is due
to the common muscular base for the trapezius and the
sternocleidomastoid muscle, which are developing from
the material of the caudal division of the branchiogenic
muscles. They also partially originate from the material of
the neck somites, that is why they are innervated from the
accesory nerve and from the ventral branches of the spinal
neck nerves (Borovanský2 etc.).
For this reason it is possible to see different anomalies
during dissection: limiting the insertion sites, different
stages of connection between trapezius and sternocleidomastoid muscle or with the occurence of accessory muscle
bundles (Le Double3, Macalister4, Testut5). The extra
bundles sometimes ascend next to the front margin of the
trapezius and can connect with the clavicular part of the
sternocleidomastoid muscle. These inconstant muscle
bundles do not have to reach the scull, but they can insert
on the transverse process of the neck vertebrae, often on
the atlas. The connection with the deltoid muscle can also
occur (Kopsch6 etc.).
Fig. 3. 1 – levator claviculae: a – origin from C1, b – origin from C2,
2 – scalenus medius, 3 – scalenus anterior, 4 – levator scapulae,
5 – sternocleidomastoid (reflected)
The demonstrated muscle (sch. 1) originates from the
front margin of the transverse process of C1 – C2 with two
flat ligaments in front of the start of the scalenus medius
(fig. 3). The muscle goes right along the front margin of
the trapezius ventrally from the levator scapulae (fig. 4)
and inserts with ligament on the back margin of the
clavicle by the conoid tubercle with the length of about 20
mm (fig. 5, 6). During its dissection we focused on the
fascial tunica, innervation and blood supply. The muscle
was covered in a separate fascial tunica that could be well
separated. Its blood supply came from the superficial
cervical artery, innervation from the ventral branches of
spinal nerves C2 – C4 (fig. 7). According to its innervation
the muscle belongs to the muscles of somatic origin. We
assume that the main function of this muscle is the elevation of the clavicle and also the lateroflection of the upper
Fig. 4. 1 – levator claviculae, 2 – levator scapulae, 3 – trapezius,
4 – scalenus medius, 5 – omohyoid, 6 – neurovascular cervical
bundle
Volume 141, 1998
55
Fig. 5. 1 – levator claviculae – its end on the clavicle, 2 – clavicle end
subclavius, 3 – deltoid muscle, 4 – cephalic vein
Fig. 7. 1 – levator claviculae, 2 – levator scapulae, 3 – trapezius,
4 – omohyoid, 5 – superficial cervical artery, 6 – ventral
branches of C1 – C2, 7 – neurovascular cervical bundle
neck spine. Kopsch6 also mentions muscles the courses
and insertions of which (under the base of the scull) are
similar – to cleidoatlanticus muscle.
REFERENCES
Fig. 6. 1 – levator claviculae, 2 – periosteum of the dorsal surface of
clavicle, 3 – scalenus anterior, 4 – scalenus medius, 5 – sternocleidomastoid (reflected), 6 – trapezius
1.
Holibková, A., Machálek, L. (1994) Contribution to Anomalies of
Dorsal Muscles. Functional and Developmental Morphology, 4 (3),
159–160.
2.
Borovanský, L. a kol. (1976) Soustavná anatomie člověka. (5.vyd.),
Avicenum, Praha.
3.
Le Double, A.F. (1897) Traité des variations du systeme musculaire
de l’homme. Schleicher Freres, Paris.
4.
Macalister, A. (1872) A Descriptive Catalogue of Muscular Anomalies in Human Anatomy. M. H. Gill, Dublin.
5.
Testut, L. (1884) Les Anomalies Musculaires Chez L’Homme. G.
Masson, Paris.
6.
Kopsch, F. (1929) Lehrbuch und Atlas der Anatomie des Menschen. Georg Thieme, Verlag, Leipzig.